Sprinkler systems are installed in buildings to reduce destruction caused by fires. A fire protection system may comprise a sprinkler system and/or a standpipe system. A sprinkler system is an active fire protection measure that provides adequate pressure and flow to a water distribution piping system, onto which a plurality of fire sprinklers is connected. Each closed-head sprinkler can be triggered once an ambient temperature around the sprinkler reaches a design activation temperature of the individual sprinkler head. In a standard wet-pipe sprinkler system, each sprinkler activates independently when the predetermined heat level is reached. Because of this, the number of sprinklers that operate is limited to only those near the fire, thereby maximizing the available water pressure over the point of fire origin. A standpipe system is another type of fire protection measure consisting of a network of vertical piping installed in strategic locations within a multi-story building. The vertical piping may deliver large volumes of water to any floor of the building to supply hose lines of firefighters, for example.
FIG. 1 illustrates a block diagram of a prior art fire pump installation 100. The fire pump installation 100 includes an electric motor driven fire pump 102 which is driven by an electric motor. The electric motor driven fire pump is further connected to a water source 104. The water source 104 provides water flow at a pressure to a fire protection system 106. Generally, fire pumps are needed when a water source cannot provide sufficient pressure to meet hydraulic design requirements of a fire protection system. This usually occurs in a building that is tall, such as a high-rise building, or in a building that requires a relatively high terminal pressure in the fire protection system 106 to provide a large volume of water, such as a storage warehouse. Thus, the fire pump 102 may be installed to boost the water source supply line pressure and maintain system pressure to meet the pressure and flow demands of the fire protection system 106.
The electric motor driven fire pump 102 starts under operation of the electric motor when a pressure in the fire protection system 106 drops below a certain predetermined start pressure. A pressure sensing line 118 is provided which allows the fire pump controller 110 to monitor system pressure. For example, the pressure in the fire protection system 106 may drop significantly when one or more fire sprinklers are exposed to heat above their design temperature, and open, releasing water. Alternately, fire hose connections to standpipe systems may be opened by firefighters causing a pressure drop in the fire protection system 106. In one instance, the fire pump may have a rating between 3 and 3500 horsepower (HP).
The fire pump installation 100 also includes an electric motor driven pressure maintenance pump, which also may be referred to as a make-up pump or a jockey pump 108. Operatively coupled to an electric motor, the jockey pump 108 is intended to maintain pressure in the fire protection system 106 so that the electric motor and hence the fire pump 102 does not need to constantly run. A pressure sensing line 120 is provided which allows the jockey pump controller 108 to monitor system pressure. For example, the jockey pump 108 maintains pressure to an artificially high level so that the operation of a single fire sprinkler will cause a pressure drop that will be sensed by a fire pump controller 110, causing the fire pump 102 to start. In some examples, the jockey pump 108 may have a rating between ¼ and 100 HP.
In one example, the jockey pump 108 may provide makeup water pressure for normal leakage within the system (such as packing on valves, seepage at joints, leaks at fire hydrants) and inadvertent use of water from the water source 104. When the fire pump 102 starts, a signal may be sent to an alarm system of a building to trigger a fire alarm. Nuisance operation of the fire pump 102 (as well as the electric motor operating the fire pump 102) may eventually cause fire department intervention and increase wear on the fire pump 102. Thus, it is generally desired to either reduce and/or avoid any nuisance or unintended operation of the fire pump 102 and accompanying fire pump motor.
The jockey pump 108 may also include a jockey pump controller 112. Each of the fire pump controller 110 and jockey pump controller 112 may comprise a microprocessor-based controller that can be used to adjust start and stop set points. For example, the fire pump controller 110 may automatically cause the fire pump 102 to start or the jockey pump controller 112 may automatically cause the jockey pump 108 to start when a water pressure is below a pressure set point. The jockey pump controller 112 may have a start pressure set point of approximately five to ten pounds per square inch (psi) greater than the start pressure point of the fire pump controller 110. In this manner, the jockey pump controller 112 cycles the jockey pump to maintain the fire protection system 106 at a predetermined pressure well above the start setting of the fire pump 102 so that the fire pump 102 only runs when a fire occurs or the jockey pump 108 is overcome by a larger than normal loss in system pressure.
The fire installation system 100 also includes check valves 114 and gate valves 116. The check valves 114 are used in the fire pump installation 100 to allow the flow of water in one direction only for the purpose of building pressure in the fire protection system 106. Check valves 114 are installed between the outlets of each of the fire pump 102 and jockey pump 108, and the fire protection system 106. The gate valves 116 are installed on the inlets and outlets of each of the fire pump 102 and jockey pump 108 and are used to isolate either the fire pump 102 or jockey pump 108 from the fire protection system 106 and water source 104 for maintenance or other purposes.